Amat Gotchi

What version is it?
Music Stars and Tama-Gos can marry using the matchmaker in the oldie stage. Music Star has to wait another 72 or so unpaused hours before the matchmaker will show up again. Tama-Go does not.
Previous versions (1-4.5) do not get the matchmaker after becoming oldies, to the best of my knowledge.

Amat Gotchi

You don't need a v4 to marry him. You just need a Tama that is version 1-4.5, raised to oldie stage (and the opposite gender). V4s can marry quite a few other versions.
I hope your Tamagotchi can have children! He should if you just pause him while you wait to have another Tamagotchi that you can marry him with.